Zinc Electrode Surface Research Articles

Electrolyte Additive l-Lysine Stabilizes the Zinc Electrode in Aqueous Zinc Batteries for Long Cycling Performance.

Rechargeable aqueous Zn-ion batteries (AZIBs) have been recognized as competitive devices for large-scale energy storage due to their characteristics of low cost, safe operation, and environmental friendliness. Nevertheless, their practical applications are greatly limited by zinc dendrite growth and side reactions occurring at the anode/electrolyte interface. Herein, we propose an effective and simple electrolyte engineering strategy, which is the introduction of l-lysine additive containing two amino groups and one carboxyl group into a ZnSO4 electrolyte to achieve stable and reversible Zn depositions. Theoretical calculations and experimental results reveal that the l-lysine can adsorb on the Zn anode surface due to the strong coordination effects between amino groups and Zn metal (Zn-N binding) and induce the reduction of ZnSO4 into inorganic ZnS, which can not only prevent interfacial side reactions but also regulate interfacial electric field on the zinc electrode surface to guide uniform Zn2+ electrodeposition to inhibit zinc dendrites. Consequently, the l-lysine additive in the electrolyte enables Zn||Zn symmetric cells to achieve an ultralong stable cycling up to 2400 h at 1 mA cm-2 with a low polarization of only about 16 mV and Zn||Cu asymmetric cells to obtain a high average Coulombic efficiency of 99.80% after stably cycling for more than 2000 h at 2 mA cm-2 (1 mAh cm-2). In addition, the Zn||MnO2@CNT full cell in an l-lysine-containing electrolyte also exhibits good cycling performance. This study offers a new perspective on multifunctional electrolyte additive for achieving highly reversible Zn metal anodes in AZIBs.

Electrolyte Optimization Strategy: Enabling Stable and Eco-Friendly Zinc Adaptive Interfacial Layer in Zinc Ion Batteries.

Aqueous zinc ion batteries (AZIBs) have emerged as a promising battery technology due to their excellent safety, high capacity, low cost, and eco-friendliness. However, the cycle life of AZIBs is limited by severe side reactions and zinc dendrite growth on the zinc electrode surface, hindering large-scale application. Here, an electrolyte optimization strategy utilizing the simplest dipeptide glycylglycine (Gly-Gly) additive is first proposed. Theoretical calculations and spectral analysis revealed that, due to the strong interaction between the amino group and Zn atoms, Gly-Gly preferentially adsorbs on zinc's surface, constructing a stable and adaptive interfacial layer that inhibits zinc side reactions and dendrite growth. Furthermore, Gly-Gly can regulate zinc ion solvation, leading to a deposition mode shift from dendritic to lamellar and limiting two-dimensional dendrite diffusion. The symmetric cell with the addition of a 20 g/L Gly-Gly additive exhibits a cycle life of up to 1100 h. Under a high current density of 10 mA cm-2, a cycle life of 750 cycles further demonstrates the reliable adaptability of the interfacial layer. This work highlights the potential of Gly-Gly as a promising solution for improving the performance of AZIBs.

Diethylene glycol dimethyl ether effectively regulates the electrochemical behavior of zinc anode

A non-proton polar solvent Diethylene glycol dimethyl ether(DGDE) was used as a cosolvent in aqueous electrolyte, the strong binding of O lone pair electrons in the CO bond to Zn2+ enabled DGDE to participate in the first solvent sheath to reconstruct the Zn2+ solvation structure. Meanwhile, the adsorption of DGDE on the surface of zinc electrode and the steric hindrance effect of DGDE molecule induced the horizontal deposition of hexagonal Zn(002) crystal plane, suppressed the zinc dendrite growth, while formed a dense protective layer on the surface of the zinc electrode to avoid it from the corrosion by the electrolyte. The initial CE of Zn‖Cu semi-battery was increased from 77 % with pure ZnSO4 electrolyte to 87 % with 0.1 M DGDE added at 0.5 mA cm−2 and 1 mAh cm−2, and the average CE at 1 mA cm−2 and 1 mAh cm−2 was maintained at 98.7 % during the long cycle. As cycled at 3C (1C = 308mAh g −1) in 0.1 M DGDE electrolyte, Zn‖ε-MnO2 full battery demonstrated much slower discharge decay, after 580 cycles, the capacity retained 138mAh g −1, 3.5 times of the system of 1 M ZnSO4. Adding trace DGDE to aqueous electrolyte can effectively improve CE and inhibit the zinc dendrite growth, not only maintains the low-cost, quick assembly advantages of aqueous zinc-ion battery, but also lays a foundation for its further application.

Dual-protected zinc anodes for long-life aqueous zinc ion battery with bifunctional interface constructed by zwitterionic surfactants

The dendrite growth on the surface of zinc anodes and formation of inactive by-products of Zn4(OH)6SO4.xH2O (ZHS), mainly attributed to the “tip effect” of an uneven surface and water corrosion of zinc anode, have seriously shrunk the anode life and hindered the commercialization of aqueous zinc ion batteries (AZIBs). Herein, we describe a bifunctional interface constructed by zwitterionic surfactant of N-decyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (Z10), which can form a polarized layer with a build-in electric field at the same time as the self-assembled hydrophobic layer on the zinc electrode surface. Two other zwitterionic surfactants including of N-octyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (Z8) and N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (Z14) are also selected, due to the different alkyl chain lengths affect the strength of the built-in electric field and the formation of hydrophobic interfaces. A combined results of experimental data with simulated calculations calculations confirm that the strength of the electric field obtained with Z10 attenuates the “tip effect” on the zinc anode surface, while accelerating the transfer of zinc ions and promoting rapid and uniform zinc plating/stripping processes. And benefited from the hydrophobic layer, the free water molecules are blocked outside the inner Helmholtz plane, lead to the suppressed ZHS formation. With the dual protection, in case of Z10, the cycle stability of the AZIBs is considerably improved to yield a long cycle lifetime of 2000 h with a coulombic efficiency of 99.4 %.

Printing 3D mesh-like grooves on zinc surface to enhance the stability of aqueous zinc ion batteries

Aqueous zinc ion batteries (AZIBs) are receiving broad attention owing to their high safety and low cost. However, the high mechanical strength and irreversible growth of zinc dendrites limit the practical application of AZIBs. Herein, regular mesh-like gullies are built on the surface of zinc foil (M150 Zn) by using simple model pressing method and stainless steel mesh as a mold. Due to the charge-enrichment effect, zinc ion deposition and stripping will be preferentially carried out in the grooves to keep the outer surface flat. In addition, zinc is exposed to 002 crystal surface in the gully after being pressed, and the deposited zinc is more inclined to grow at a small angle, so that it has a sedimentary morphology parallel to the basement. Consequently, at a current density of 0.5 mA cm−2, the M150 zinc anode has a voltage hysteresis of only 35 mV and a cycle life of up to 400 h (relative to a zinc foil of 96 mV and 160 h). Even more imposing is that the full cell has a capacity retention of approximately 100% after 1000 cycles at 2 A g−1 and a specific capacity of almost 60 mAh g−1 when activated carbon is used as the cathode. It is a promising method to improve the stable cycle performance of AZIBs by using a simple method to realize the non-prominent dendrites on the surface of zinc electrode.

Multifunctional water-organic hybrid electrolyte for rechargeable zinc ions batteries

Uncontrollable dendrite growth and parasitic reactions are the fundamental obstacles to achieve large-scale application of aqueous Zn-ion batteries. Herein, a new strategy of tuning the electrolyte solvation structure and electrode interface is demonstrated for highly reversible zinc plating/stripping. Acetonitrile (AN) is introduced into Zn(OTf)2 electrolyte as co-solvent, the interaction between Zn2+ and acetonitrile attenuates the Zn2+ solvation and water activity. Concomitantly, theoretical calculations demonstrate that acetonitrile molecules tend to adsorb on the surface of zinc electrode to form an adaptive zinc-electrolyte interface. Such an electrolyte engineering significantly prevents water hydrogen evolution, suppresses vanadium dissolution and modulates Zn deposition behavior. As proof of concept, Zn//Zn symmetric cells with acetonitrile additive exhibit a ultra-long cycling of 2100 h at a high current density of 5 mA cm−2. In particular, the university of the acetonitrile–water co-solvent (AWCS) electrolyte is demonstrated, multiple battery systems (Zn//Al-V-O, Zn//Zn-V-O, Zn//VOOH, and Zn//Mn-V-O) deliver markedly improved cycling stability and rate performance. The mechanism of action of AWCS electrolyte on performance indicators is discussed in detail, which provides a promising insight for energy storage devices.

Modifying hydrogel electrolyte to induce zinc deposition for dendrite-free zinc metal anode

In recent years, flexible devices have promoted extensive research on flexible aqueous Zn-ion batteries (ZIBs). Nevertheless, the dendrite growth on the anode and the poor mechanical properties of the flexible polymer electrolyte have become bottle-necks for the practical applications of flexible ZIBs. Herein, Carboxymethyl cellulose/polyacrylamide (CMC/PAM) hydrogel electrolyte has been constructed for flexible ZIBs. By introducing double-network structure, we dramatically improve the mechanical properties of the hydrogel electrolyte. The electrostatic interaction between carboxyl groups and Zn2+ can evenly induce the deposition of zinc ions on the zinc electrode surface, leading to remarkable reversibility and stability of zinc electrode. Flexible full ZIBs assembled with this electrolyte exhibit competitive electrochemistry performance with 90.18% capacity retention over 500 cycles at 0.308 mA cm−2. Furthermore, such ZIBs offer excellent bending resistance for enduring high mechanical impact. This study provides an effective strategy to address the zinc dendrite issue and reliability of flexible ZIBs.

Corrosion Inhibition and Passivation Delay Action of Lauroamide Propylbetaine on Zinc in Alkaline Medium

The effects of lauroamide propylbetaine on zinc corrosion and passivation are investigated in 7.0 M KOH solution saturated with ZnO by Tafel polarization curve, electrochemical impedance spectroscopy and linear sweep voltammetry. It demonstrates that lauroamide propylbetaine acts as cathodic-type inhibitor and restrains zinc corrosion in alkaline medium through reducing the hydrogen evolution. With increasing concentrations of lauroamide propylbetaine, the corrosion inhibition effect and charge transfer resistance of zinc electrode enhance, and the corrosion inhibition efficiency reaches up to 84.1% in the presence of 800 ppm lauroamide propylbetaine. It is confirmed that the adsorption of lauroamide propylbetaine on the surface of zinc electrode follows Langmuir isotherm model. Besides, anodic polarization curves suggest that a small quantity of lauroamide propylbetaine is advantageous to delay the passivation of zinc electrode. Results reveal that the corrosion of zinc surface is alleviated in alkaline medium in the presence of 800 ppm lauroamide propylbetaine.

Effects of dodecyltrimethylammonium bromide surfactant on both corrosion and passivation behaviors of zinc electrodes in alkaline solution

The corrosion and passivation behaviors of zinc electrodes in 7.0 M KOH saturated with ZnO in the presence of dodecyltrimethylammonium bromide (DTAB) surfactant were evaluated by Tafel, linear sweep voltammetry, electrochemical impedance spectroscopy (EIS) and field emission scanning electron microscopy (FE-SEM) tests. It was found that DTAB had a considerable effect on inhibiting zinc corrosion by the adsorption of DTAB. The adsorption of DTAB obeyed the Freundlich isotherm. Tafel polarization curves revealed that DTAB worked as an anodic-type inhibitor. The highest corrosion inhibition efficiency of DTAB was up to 80.2% in the presence of 0.07 wt% DTAB. In addition, potentials of both passivation and anodic dissolution current peak positively shifted in the presence of DTAB, indicating that the passivation was delayed. Based on the EIS tests and FE-SEM analysis in the presence and absence of DTAB, it was shown that the adsorption and favorable moisture retention of DTAB were beneficial to the formation of uniform and fluffy protective layer on the surface of zinc electrode. Such a morphological modification of zinc surface greatly improved the diffusion rate of ions and the utilization of zinc electrode.

Preparation of Schiff base surfactant and its application in alkaline zinc-nickel batteries

A Schiff base surfactant 2-octanone ethylenediamine (OED) was in this study designed to improve the performance of alkaline zinc-nickel batteries that were synthesized and characterized by IR and XRD. Electrochemical experimental results showed that addition of OED surfactant in both zinc electrode and electrolyte effectively inhibited self-corrosion of zinc electrode and improved performance of zinc-nickel battery charge and discharge. The battery capacity can keep almost 70 % of the theoretical capacity after 30 times cycles. The batteries also showed better performance, lower resistance, and longer cycle life with addition of surfactant, which can be attributed to fact that the zinc electrode surface had good adsorption capacity and coordination with zinc ions in the presence of surfactant.

Effects of Carboxymethyl Cellulose on the Electrochemical Characteristics and Dendrite Growth of Zinc in Alkaline Solution

Carboxymethyl cellulose (CMC) is an important additive for zinc paste electrodes in alkaline zinc-based batteries. However, while its use is increasingly common in zinc paste electrodes, no research exists regarding the electrochemical effects of CMC on the zinc electrode surface. The present study investigates the influence of different contents of CMC in 6 M KOH on a pure zinc electrode with a flat surface. The corrosion potential, corrosion current density, and polarization resistance are assessed by Tafel extrapolation, which shows that CMC could reduce the corrosion current and lower the hydrogen evolution potential. Electrochemical impedance spectroscopy and potentiodynamic and galvanostatic anodic polarization confirm that CMC in the alkaline electrolyte could increase corrosion resistance but inhibit the discharge process of alkaline zinc-based batteries. Scanning electron microscopy indicates that 10 g L−1 or more CMC could suppress zinc electrodeposition kinetics and change the crystalline morphology. These results demonstrate that an appropriate amount of CMC in 6 M KOH can suppress the rates of corrosion and zinc dendrite growth.

Effects of MoO3 on secondary alkaline zinc anode

MoO3 was added to the zinc electrode of Zn/KOH/NiOOH cells. The combination of anodic polarization curve, constant current charge–discharge, and impedance spectra was used to investigate the effects of adding MoO3 on the electrochemical performance of zinc anode. The cell with MoO3 added in zinc anode reached 360 cycles before its capacity fell below 90 % of the initial capacity, while the cell without MoO3 failed after 180 cycles. Based on the scanning electron microscopy observation, the significant improvement of cycle stability can be attributed to the addition of MoO3, which helps zinc electrode to stay in a loose and porous structure, such texture is definitely in favor of the diffusion of OH− ions, facilitating the utilization of active material. But for standard electrode without MoO3, zinc anode is easy to passivate owing to the formation of dense ZnO film on zinc electrode surface. This compact film restricts OH− ion diffusion and decreases active area of zinc electrode. Therefore, MoO3-added electrode can effectively improve the cycle performance of the Ni–Zn battery.

Effect of Nanocomposite Additives on Corrosion Inhibition of Zn Anode in Neutral Solution

Effects of hexadecyl trimethyl ammonium bromide (CTAB), polyethylene glycol nanowire (NPEG) and their nanocomposite additives on corrosion inhibition of Zn in 1 mol/L ZnSO4 solution were investigated by weight-loss measurements, electrochemical tests，scanning electron microscopy and battery discharge tests. The results show that the inhibition efficiency of nanocomposite additives is 70%, which is much higher than individual inhibitors of CTAB or NPEG alone, because of the notable synergistic effect between CTAB and NPEG. While CTAB can cause a negative shift of corrosion potential of zinc, NPEG can form a very thick hydrophobic layer on the surface of zinc electrode by adsorption. Furthermore, NPEG can render part of CTAB cations to form large micelle particles along the NPEG macromolecular chains and cross-link with NPEG, and thus greatly enhance the blocking effect of the hydrophobic layer. Therefore，the corrosion inhibition efficiency of the composite additives is much higher. The battery containing 0.05% CTAB and 0.05% NPEG performs better than the batteries with individual additives, especially at high discharge current rate.

Effect of some amidopoly ethylamine on corrosion of zinc electrode used in zinc-manganese batteries

The effect of addition of some amidopoly ethylamine, with different numbers of ethylamine units, on the corrosion of zinc electrode in 35% ZnCl2, (26% ZnCl2 + 8.8% NH4Cl), (8.8% ZnCl2 + 26% NH4Cl) and 26% NH4Cl electrolytes has been studied using galvanostatic polarization measurements and hydroden evolution reaction (HER). The effect of the addition on discharge and shelf life of Zn-manganese batteries has been studied. The results showed that the inhibition efficiency increases with increasing number of ethylamine units per molecule. Inhibition is explained on the basis of adsorption of amidopoly ethylamine molecules on the zinc electrode surface through their ethylamine groups.

Amidopoly Ethylamines as Corrosion Inhibitors for Zinc Dissolution in Different Acidic Electrolytes

The effect of some amidopoly ethylamine, with different numbers of ethylamine units, on the corrosion of zinc electrode in ZnCl 2, NH 4Cl and (ZnCl 2 + NH 4Cl) electrolytes has been studied using galvanostatic polarization measurements. The inhibition efficiency was found to increase with increasing concentration, number of ethylamine units per molecule and with decreasing the temperature. Inhibition is explained on the basis of adsorption of amidopoly ethylamine molecules on the zinc electrode surface through their ethylamine groups. The inhibitors are adsorbed on the zinc electrode surface according to Langmuir adsorption isotherm. Some thermodynamic parameters are calculated and explained for the tested systems from the data obtained at different temperatures.

Ionic Mass Transfer Accompanying Anodic Dissolution of Zinc in Alkaline Solution

Holographic interferometry was applied in situ to measure the ionic mass-transfer rates near upward-facing zinc anodes dissolving at high current densities in aqueous KOH solutions. The time-varying interference fringe patterns were converted to individual concentration profiles of , , and ions. The measured ionic concentration profiles agreed well with those predicted by a transient diffusion model for a multicomponent electrolyte. When a zinc anode was electrochemically dissolved in KOH electrolyte, the anode potential abruptly shifted in the noble direction, immediately followed by gas evolution. The onset time for this potential rise and accompanying gas evolution agreed well with the calculated time interval required to drive the ion concentration to zero at the zinc electrode surface. The present model can be applied to not only optimize zinc cell designs but also develop a control method for trouble-free, safe operation of a zinc battery without gas evolution.

Charge–discharge characteristics of nickel/zinc battery with polymer hydrogel electrolyte

A new nickel/zinc (Ni/Zn) battery was assembled by using polymer hydrogel electrolyte prepared from cross-linked potassium poly(acrylate) and KOH aqueous solution, and its charge–discharge characteristics were investigated. The experimental Ni/Zn cell with the polymer hydrogel electrolyte exhibited well-defined charge–discharge curves and remarkably improved charge–discharge cycle performance, compared to that with a KOH aqueous solution. Moreover, it was found that dendritic growth hardly occurred on the zinc electrode surface during charge–discharge cycles in the polymer hydrogel electrolyte. These results indicate that the polymer hydrogel electrolyte can successfully be used in Ni/Zn batteries as an electrolyte with excellent performance.

Zinc hexacyanoferrate film as an effective protecting layer in two-step and one-step electropolymerization of pyrrole on zinc substrate

The two-step and one-step electrosynthesis processes of polypyrrole (PPy) films on the zinc substrate are described. The two-step process includes (i) the zinc surface pretreatment with hexacyanoferrate ion in the aqueous medium in order to form a zinc hexacyanoferrate (ZnHCF) film non-blocking passive layer on the surface and with the view to prevent its reactivity and (ii) electropolymerization of pyrrole on the ZnHCF|Zn-modified electrode in aqueous pyrrole solution. In this context, both the non-electrolytic and electrolytic procedures were adapted, and the effect of some experimental conditions such as supporting electrolyte, pH and temperature of the solution at the zinc surface pretreatment step as well as pyrrole concentration and electrochemical techniques at the polymerization step was investigated. By optimizing the experimental conditions in both steps, we have obtained a homogeneous and strongly adherent PPy films on the zinc substrate. The one-step process is based on the use of an aqueous medium containing Fe(CN) 6 4− and pyrrole. The ferrocyanide ion passivates the substrate by formation of ZnHCF film during the electropolymerization process of pyrrole and therefore makes it possible to obtain strongly adherent PPy films, with controlled thickness, either by cyclic voltammetry or by electrolysis at constant current or constant potential without any previously treatment of the zinc electrode surface. The polypyrrole films deposited on the zinc electrode were characterized by cyclic voltammetry and scanning electron microscopic (SEM) measurement.

Kinetic Regularities of Zinc Corrosion in Chromating Baths

Electrochemical modeling of zinc corrosion in chromate solutions showed that its rate (which is controlled by the limiting current density of Cr(VI) reduction to Cr(III)) is determined by the limiting diffusion current of hydrogen ions to the zinc electrode surface partially covered with the chromate coating. The sizes of active and passive surface sites are comparable with the thickness of the diffusion layer of the solution, which means that the zinc surface corroding in a chromate solution is macroscopically heterogeneous. Investigating the kinetics of the electrode reactions showed that, in the absence of a noticeable film formation, the steady-state cathodic polarization curve of zinc in sulfate–chromate solutions can be described by a kinetic equation that takes into account the pH s dependence on the dissolution rate of zinc.

Self-healing protective films prepared on zinc by treatments with cerium(III) nitrate and sodium phosphate

Chromate-free, self-healing protective films were prepared on a surface of zinc electrode previously treated in a solution of cerium(III) nitrate Ce(NO 3) 3 by coverage of the surface with a layer of sodium phosphate Na 3PO 4. The self-healing ability of the film was examined by polarization measurements of the electrode after scratching the surface with a knife-edge crosswise and immersed in an aerated 0.5 M NaCl solution for many hours and by observation of pit formation at the scratches. A thin film containing 0.0552 mg/cm 2 of Na 3PO 4·12H 2O prepared on the electrode previously treated in 1×10 −3 M Ce(NO 3) 3 at 30 °C for 30 min and dried at 90 °C for 23 h was highly self-healing and protective against corrosion of zinc in 0.5 M NaCl at the scratches. No pit was detected at the scratches on the electrode coated with this film after immersion for 72 h.